package com.alibaba.nacos.console.utils;

import org.apache.commons.codec.binary.Base64;

import javax.crypto.Cipher;
import java.security.*;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.HashMap;
import java.util.Map;

/**
 * Created by 王皓 on 17-4-12.
 */
public class RsaUtil {

    public static final String KEY_ALGORITHM = "RSA";

    public static final String SIGNATURE_ALGORITHM = "MD5withRSA";

    private static final String PUBLIC_KEY = "RSAPublicKey";

    private static final String PRIVATE_KEY = "RSAPrivateKey";

    public static byte[] decryptBase64(String key) {
        return Base64.decodeBase64(key);
    }

    public static String encryptBase64(byte[] bytes) {
        return Base64.encodeBase64String(bytes);
    }

    /**
     * 用私钥对信息生成数字签名
     *
     * @param data       加密数据
     * @param privateKey 私钥
     */
    public static String sign(byte[] data, String privateKey) throws Exception {
        // 解密由base64编码的私钥
        byte[] keyBytes = decryptBase64(privateKey);
        // 构造PKCS8EncodedKeySpec对象
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        // KEY_ALGORITHM 指定的加密算法
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        // 取私钥匙对象
        PrivateKey priKey = keyFactory.generatePrivate(pkcs8KeySpec);
        // 用私钥对信息生成数字签名
        Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
        signature.initSign(priKey);
        signature.update(data);
        return encryptBase64(signature.sign());
    }

    /**
     * 校验数字签名
     *
     * @param data      加密数据
     * @param publicKey 公钥
     * @param sign      数字签名
     * @return 校验成功返回true 失败返回false
     */
    public static boolean verify(byte[] data, String publicKey, String sign)
        throws Exception {
        // 解密由base64编码的公钥
        byte[] keyBytes = decryptBase64(publicKey);
        // 构造X509EncodedKeySpec对象
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
        // KEY_ALGORITHM 指定的加密算法
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        // 取公钥匙对象
        PublicKey pubKey = keyFactory.generatePublic(keySpec);
        Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
        signature.initVerify(pubKey);
        signature.update(data);
        // 验证签名是否正常
        return signature.verify(decryptBase64(sign));
    }

    /**
     * 使用私钥解密密文
     *
     * @param data 密文经过base64编码后的byte数组
     * @param key  密钥
     * @return 解密后明文的byte数组
     * @throws GeneralSecurityException 解密过程中的通用安全异常
     */
    public static byte[] decryptByPrivateKey(byte[] data, String key) throws GeneralSecurityException {
        // 对密钥解密
        byte[] keyBytes = decryptBase64(key);
        // 取得私钥
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key privateKey = keyFactory.generatePrivate(pkcs8KeySpec);
        // 对数据解密
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.DECRYPT_MODE, privateKey);
        return cipher.doFinal(data);
    }

    /**
     * 解密<br>
     * 用私钥解密
     */
    public static byte[] decryptByPrivateKey(String data, String key) throws GeneralSecurityException {
        return decryptByPrivateKey(decryptBase64(data), key);
    }

    /**
     * 解密<br>
     * 用公钥解密
     */
    public static byte[] decryptByPublicKey(byte[] data, String key)
        throws Exception {
        // 对密钥解密
        byte[] keyBytes = decryptBase64(key);
        // 取得公钥
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key publicKey = keyFactory.generatePublic(x509KeySpec);
        // 对数据解密
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.DECRYPT_MODE, publicKey);
        return cipher.doFinal(data);
    }

    /**
     * 加密<br>
     * 用公钥加密
     */
    public static byte[] encryptByPublicKey(String data, String key)
        throws Exception {
        // 对公钥解密
        byte[] keyBytes = decryptBase64(key);
        // 取得公钥
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key publicKey = keyFactory.generatePublic(x509KeySpec);
        // 对数据加密
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.ENCRYPT_MODE, publicKey);
        return cipher.doFinal(data.getBytes());
    }

    /**
     * 加密<br>
     * 用私钥加密
     */
    public static byte[] encryptByPrivateKey(byte[] data, String key)
        throws Exception {
        // 对密钥解密
        byte[] keyBytes = decryptBase64(key);
        // 取得私钥
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key privateKey = keyFactory.generatePrivate(pkcs8KeySpec);
        // 对数据加密
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.ENCRYPT_MODE, privateKey);
        return cipher.doFinal(data);
    }

    /**
     * 取得私钥
     */
    public static String getPrivateKey(Map<String, Key> keyMap) {
        Key key = keyMap.get(PRIVATE_KEY);
        return encryptBase64(key.getEncoded());
    }

    /**
     * 取得公钥
     */
    public static String getPublicKey(Map<String, Key> keyMap) {
        Key key = keyMap.get(PUBLIC_KEY);
        return encryptBase64(key.getEncoded());
    }

    /**
     * 初始化密钥
     */
    public static Map<String, Key> initKey() throws Exception {
        KeyPairGenerator keyPairGen = KeyPairGenerator
            .getInstance(KEY_ALGORITHM);
        keyPairGen.initialize(1024);
        KeyPair keyPair = keyPairGen.generateKeyPair();
        Map<String, Key> keyMap = new HashMap<>(2);
        keyMap.put(PUBLIC_KEY, keyPair.getPublic()); // 公钥
        keyMap.put(PRIVATE_KEY, keyPair.getPrivate()); // 私钥
        return keyMap;
    }

    public static String encryptByPublicKeyToString(String passPwd, String publicKey) throws Exception {
        return Base64.encodeBase64String(encryptByPublicKey(passPwd, publicKey));
    }
}
